Method, controller, data center, system and storage medium for network charging

ABSTRACT

Disclosed is a method for network charging, which includes: a data center management network element, upon reception of a charging resource request message from a controller, supports a charging function of a processing network element by a virtual machine and feeding back information of the processing network element to the controller; the data center management network element sending charging strategy information, user state information and information of UGW to the processing network element, which implements transmission of a traffic flow with the UGW according to the information of UGW, charges for the traffic flow according to the charging strategy information and the user state information, and feeds back charging processing information to the data center management network element; and the data center management network element feeding back the charging processing information to the controller. The disclosure further provides a data center, controller, UGW and system for network charging. Thus the charging service may be implemented for a SDN EPC network.

TECHNICAL FIELD

The embodiments of the disclosure relate to a software-defined networktechnology, the data centre virtualization technology and the 3rdGeneration Partnership Project (3GPP)—packet domain (PS) core networktechnology, and in particular to a method, a controller, a data centre,a system and storage medium for network charging.

BACKGROUND

In 2008, Stanford University in the U.S.A. proposed an Open Flowprotocol which uses an architecture in which forwarding plane andcontrol plane are separated. In the architecture of the Open Flowprotocol, a control plane entity takes use of a controller based on theOpen Flow protocol to implement forwarding logics, while a forwardingplane entity takes use of a gateway based on the Open Flow protocol toimplement controlled forwarding according to a flow table issued fromthe controller. The behaviour of the gateway is standardised. Forexample, after receiving a message, the gateway analyses the message toobtain the header, i.e. L2/L3/L4 related field values, and takes thesevalues as the keywords for searching the flow table, and after an itemin the flow table is matched, transforms the message field based on theinstruction set in the content of the item, forwards the message to acertain logical or physical port according to the instruction of theitem when the transformation is terminated. A Software Defined Network(SDN) is a further evolution of the Open Flow protocol. The SDN mayimplement a variety of complex network applications in the manner ofsoftware programming on the control plane without any change of theforwarding plane devices. Moreover, since the control plane takes use ofuniversal servers and universal systems, universal software programmingtools or computer programming languages such as Python may be used forimplementing script programming. Thus, the implementation of novelnetwork protocols through the forwarding plane becomes extremely simpleand the deployment cycle of new technologies is reduced significantly.

An Evolved Packet Core (EPC) network is a novel packet core networkintroduced in the phase of 3GPP R8. The EPC leads to further flattenednetworks, in which devices on the forwarding plane are further dividedinto a Serving Gateway (SGW) and a PDN Gateway (PGW). Since the R8, theEPC has a series of enhanced functions, including introducedtechnologies such as traffic offload. These enhanced functions requiresa period of 1 to 2 years for formulating new protocol specifications andthen they are implemented by equipment suppliers, tested and deployed byoperators. Thus, the introduction cycle of new network characteristicsbecomes long and costly. The Open Flow protocol aims at overcoming theseproblems. The introduction of a new characteristic of network may beachieved by only modifying the logic of the control network element,i.e. controller, in the Open Flow protocol, the controller controllingdevices on the forwarding plane to implement this new function, whichleads to a fast introduction of new network functions. However, the OpenFlow protocol is currently mainly applied to layer-2 switching networks.It cannot support directly the network elements in EPC on which servicecontrol are needed. The introduction of the Open Flow mechanism willaffect functions and control modes of existing user plane networkelements in the EPC.

FIG. 1 is a schematic diagram illustrating the system architecture of aSDN EPC. The Unified Gateway (UGW) in FIG. 1 merely has user planefunctions. All the control plane functions are implemented by thecontroller. The user plane functions includes: establishment,modification, assurance of Quality of Service (QoS) of a user planetunnel, etc. The UGW may be divided into SGW and PGW according to itsfunction under the logic control of the controller. The SGW and PGW areessentially UGWs with same functions, which enable the EPC to implementmore flexible networking, and the controller may introduce applicationfunctions flexibly through an Application Program Interface (API) toenhance the capability of the EPC.

As the basic requirement of operators to a network, the implementationof a charging function should also be considered in the case of an EPCnetwork based on SDN. In the prior art, a Charging Trigger Function(CTF), a Charging Data Function (CDF) and a Charging Gateway Function(CGF) are integrated in a PGW, which is responsible for collection ofcharging information and credit control, and supports the interface tothe charging system network element, so as to implement functions ofoffline/online charging and content charging. In view of implementation,compared with UGWs in a SDN network, charging function packet gatewaysin the prior art require logical control operations related to chargingin addition to a forwarding function, leading to complex logics and highcost without universality, thus being no longer adapted for the newgeneration mobile communication network in which the control andforwarding are separated.

SUMMARY

In order to address the above problems, the embodiments of the presentdisclosure provide a method, a controller, a data centre and system andstorage medium for network charging, enabling the charging service to beimplemented for a SDN EPC network and executed simply with low cost andhigh universality.

The technical scheme of the present disclosure is implemented asfollows:

A method for network charging includes:

upon reception of a charging resource request message from a controller,a data centre management network element supports a charging function ofa processing network element by a virtual machine and feeds backinformation of the processing network element to the controller, whereinthe charging resource request message comprises charging strategyinformation, user state information and information of a universalgateway (UGW);

the data centre management network element sends the charging strategyinformation, the user state information and the information of the UGWto the processing network element;

the processing network element implements transmission of a traffic flowwith the UGW according to the information of the UGW, charges for thetraffic flow according to the charging strategy information and the userstate information, and feeds back charging processing information to thedata centre management network element; and

the data centre management network element feeds back the chargingprocessing information to the controller.

The method may further include: upon reception of the chargingprocessing information from an online charging system, the data centremanagement network element feeds back the charging processinginformation to the controller.

The information of the processing network element may include address ortunnel information of the processing network element;

the charging strategy information may include a charging level, acharging mode, a measurement method and a data usage report level;

the user state information may include a user identifier, user locationinformation, service network information, an access network type, closeduser group (CSG) information, and a charging feature for a subscriber;and

the information of the UGW may include address or tunnel information ofthe UGW.

When the processing network element performs online charging, thecharging for the traffic flow according to the charging strategyinformation and the user state information may include:

the processing network element requests and acquires a credit quota ofeach charging level from the online charging system, the credit quotacomprising traffic and duration;

the processing network element calculates traffic and duration of thetraffic flow, and monitors a usage extent of the credit quota of eachcharging level; and

the processing network element sends a credit quota control updatemessage to the online charging system and acquires an updated creditquota when the credit quota is expired.

When the processing network element performs offline charging, thecharging for the traffic flow according to the charging strategyinformation and the user state information may include:

the processing network element calculates traffic and duration of thetraffic flow according to the charging strategy information and the userstate information, and monitors triggering of a charging event.

When the processing network element performs online charging, the methodmay further include:

upon reception of a user state information change notification messagefrom the controller, the data centre management network element sendsthe user state information change notification message to the processingnetwork element;

when a charging event is triggered and a credit quota is re-granted, theprocessing network element sends a credit quota control update messageto the online charging system and acquires an updated credit quota;

when the credit quota in the online charging system is expired, theonline charging system sends a session termination message to the datacentre management network element.

When the processing network element performs offline charging, themethod may further include:

upon reception of a user state information change notification messagefrom the controller, the data centre management network element sendsthe user state information change notification message to the processingnetwork element;

when the charging event is triggered, the processing network elementsends the charging event and traffic and duration of the traffic flow toan offline charging system through a billing message: or, the processingnetwork element sends a charging data record (CDR) of a generatedcalling record to the offline charging system through a data recordtransmission message.

The method may further include that when a session is terminated, thedata centre management network element notifies the controller of asession termination message and releases a user plane channel/link bymeans of the controller;

when a session or a packet data protocol (PDP) context is deleted, thedata centre management network element receives a charging-relatedsession releasing message from the controller and notifies theprocessing network element to terminate charging and to report chargingprocessing information;

the data centre management network element releases resources related tothe processing network element and deletes the charging strategyinformation, the user state information and the information of the UGW.

A method for network charging includes:

user state information is received from a mobility management networkelement and charging strategy information is received from a chargingrule network element, then a charging resource request messagecontaining the charging strategy information, the user state informationand information of a universal gateway (UGW) are sent to a data centremanagement network element;

information of a processing network element is received from the datacentre management network element;

a flow table for the UGW is configured according to the information ofthe processing network element, and the configured flow table is sent tothe UGW; and

charging processing information fed back from the data centre managementnetwork element is received when the processing network element chargesfor a traffic flow.

The information of the processing network element may include address ortunnel information of the processing network element;

the charging strategy information may include a charging level, acharging mode, a measurement method and a data usage report level;

the user state information may include a user identifier, user locationinformation, service network information, an access network type, CSGinformation and a charging feature for a subscriber; and

the information of the UGW may include address or tunnel information ofthe UGW.

The method may further include that a user state information changenotification message is sent to the data centre management networkelement, upon reception of the user state information changenotification message from the mobility management network element.

The method may further include that:

when a session is terminated, a session termination message sent fromthe data centre management network element is received and a user planechannel/link is released;

when a session or a PDP context is deleted, a charging-related sessionreleasing message is sent to the data centre management network element.

A data centre includes a data centre management network element and aprocessing network element, in which

the data centre management network element is configured to, uponreception of a charging resource request message from a controller,support a charging function of a processing network element by a virtualmachine and feed information of the processing network element back tothe controller, wherein the charging resource request message comprisescharging strategy information, user state information and information ofa universal gateway (UGW); and configured to send the charging strategyinformation, the user state information and the information of the UGWto the processing network element, feed charging process informationwhich is fed back from the processing network element back to thecontroller;

the processing network element is configured to implement transmissionof a traffic flow with the UGW according to the information of the UGW,charge for the traffic flow according to the charging strategyinformation and the user state information, and feed the chargingprocessing information back to the data centre management networkelement.

The data centre may further include an online charging system configuredto send the charging processing information to the data centremanagement network element;

the data centre management network element is further configured to feedthe charging processing information from the online charging system backto the controller.

The information of the processing network element may include address ortunnel information of the processing network element;

the charging strategy information may include a charging level, acharging mode, a measurement method and a data usage report level;

the user state information may include a user identifier, user locationinformation, service network information, an access network type, CSGinformation, and a charging feature for a subscriber; and

the information of the UGW may include address or tunnel information ofthe UGW.

when the processing network element performs online charging, theprocessing network element is further configured to request and acquirea credit quota of each charging level from the online charging system,the credit quota comprising traffic and duration, calculate traffic andduration of the traffic flow, and monitor a usage extent of the creditquota of each charging level; and configured to send a credit quotacontrol update message to the online charging system and acquire anupdated credit quota when the credit quota is expired;

the online charging system is configured to provide the credit quota ofeach charging level to the processing network element when receiving therequest from the processing network element, and provide the updatedcredit quota to the processing network element upon reception of thecredit quota control update message from the processing network element.

When the processing network element performs online charging, theprocessing network element is further configured to calculate trafficand duration of the traffic flow according to the charging strategyinformation and the user state information, and monitor triggering of acharging event.

When the processing network element performs online charging, the datacentre management network element may be further configured to, uponreception of a user state information change notification message fromthe controller, send the user state information change notificationmessage to the processing network element;

the processing network element is further configured to, when a chargingevent is triggered and a credit quota is re-granted, send a credit quotacontrol update message to the online charging system and acquire anupdated credit quota;

the online charging system is further configured to, when the creditquota in the online charging system is expired, send a sessiontermination message to the data centre management network element.

When the processing network element performs offline charging, the datacentre may further include an offline charging system,

the data centre management network element is further configured to,upon reception of a user state information change notification messagefrom the controller, send the user state information change notificationmessage to the processing network element;

the processing network element is further configured to, when thecharging event is triggered, send the charging event and traffic andduration of the traffic flow to an offline charging system through abilling message; or, send a generated CDR to the offline charging systemthrough a data record transmission message;

the offline charging system is configured to receive from the processingnetwork element the charging event and a calculation result of thetraffic and duration of the traffic flow, or the CDR.

The data centre management network may be further configured to, when asession is terminated, notify the controller of a session terminationmessage and release a user plain channel/link by means of thecontroller; when a session or a packet data protocol (PDP) context isdeleted, receive a charging-related session releasing message from thecontroller and notify the processing network element to terminatecharging and to report charging processing information; releaseresources related to the processing network element, and delete thecharging strategy information, the user state information and theinformation of the UGW.

A controller includes a first receiving unit, a first sending unit, asecond receiving unit, a configuration unit, a second sending unit and athird receiving unit, in which

the first receiving unit is configured to receive user state informationfrom a mobility management network element and charging strategyinformation from a charging rule network element;

the first sending unit is configured to send a charging resource requestmessage containing the charging strategy information, the user stateinformation and information of a UGW to a data centre management networkelement;

the second receiving unit is configured to receive information of aprocessing network element from the data centre management networkelement;

the configuration unit is configured to configure a flow table for theUGW according to the information of the processing network element;

the second sending unit is configured to send the configured flow tableto the UGW; and

the third receiving unit is configured to receive charging processinginformation fed back from the data centre management network elementwhen the processing network element charges for a traffic flow.

The information of the processing network element may include address ortunnel information of the processing network element;

the charging strategy information may include a charging level, acharging mode, a measurement method, and a data usage report level;

the user state information may include a user identifier, user locationinformation, service network information, an access network type, CSGinformation, and a charging feature for a subscriber; and

the information of the UGW may include address or tunnel information ofthe UGW.

The controller may further include a third sending unit configured tosend a user state information change notification message to the datacentre management network element, upon reception of the user stateinformation change notification message from the mobility managementnetwork element.

The controller may further include a releasing unit and a fourth sendingunit, in which

wherein the releasing unit is configured to, when a session isterminated, receive a session termination message from the data centremanagement network element and release a user plane channel/link;

the fourth sending unit is configured to, when a session or a packetdata protocol PDP context is deleted, send a charging-related sessionreleasing message to the data centre management network element.

A system for network charging includes any data centre as describedabove, any controller as described above and a UGW.

A storage medium which stores a computer programme configured to executethe method for network charging as described above.

The embodiments of the present disclosure provide a method, acontroller, a data centre and a system for network charging, in which adata centre management network element supports, upon reception of acharging resource request message from a controller, a charging functionof a processing network element by a virtual machine and feeds backinformation of the processing network element to the controller; whereinthe charging resource request message comprises charging strategyinformation, user state information and information of a universalgateway (UGW); the data centre management network element sends thecharging strategy information, the user state information and theinformation of the UGW to the processing network element, then, theprocessing network element implements transmission of a traffic flowwith the UGW according to the information of the UGW, charges for thetraffic flow according to the charging strategy information and the userstate information, and feeds back charging processing information to thedata centre management network element; and the data centre managementnetwork element feeds back the charging processing information to thecontroller. In this way, a SDN EPC network can be charged simply withlow cost and high universality.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the system architecture of a SDN EPC;

FIG. 2 is a first schematic diagram of an implementation procedure of amethod for network charging according to an embodiment of the presentdisclosure;

FIG. 3 is a second schematic diagram of an implementation procedure of amethod for network charging according to an embodiment of the presentdisclosure;

FIG. 4 is a schematic diagram of the structural composition of a datacentre according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram of the structural composition of acontroller according to an embodiment of the present disclosure;

FIG. 6 is a schematic diagram of the structural composition of a systemfor network charging according to an embodiment of the presentdisclosure;

FIG. 7 is a schematic diagram of an implementation procedure of a methodof online charging according to an embodiment of the present disclosure;

FIG. 8 is a schematic diagram of an implementation procedure of a methodof offline charging according to an embodiment of the presentdisclosure; and

FIG. 9 is a schematic diagram of an implementation procedure of a methodof network content charging according to an embodiment of the presentdisclosure.

DETAILED DESCRIPTION

The characteristics and technical contents of the present disclosure areillustrated in further detail through a detailed description of theimplementation of the present disclosure with reference to accompanyingfigures, which are merely used for illustration but not for limitation.

An embodiment of the present disclosure describes a method for networkcharging performed by a data centre. As shown in FIG. 2, said methodincludes following steps:

Step 201: upon reception of a charging resource request message from acontroller, a data centre management network element supports a chargingfunction of a processing network element by a virtual machine and feedsback information of the processing network element to the controller.

The charging resource request message includes charging strategyinformation, user state information and information of a UGW.

Preferably, the method further includes that upon reception of chargingprocessing information from an online charging system, the data centremanagement network element feeds back the charging processinginformation to the controller.

Preferably, the information of the processing network element comprisesaddress or tunnel information of the processing network element;

the charging strategy information includes a charging level, a chargingmode, a measurement method and a data usage report level;

the user state information includes a user identifier, user locationinformation, service network information, an access network type, closeduser group (CSG) information, and a charging feature for a subscriber;

the information of the UGW includes address or tunnel information of theUGW.

When the processing network element performs online charging, thecharging for the traffic flow according to the charging strategyinformation and the user state information includes:

the processing network element requests and acquires a credit quota ofeach charging level from the online charging system, the credit quotaincluding traffic and duration;

the processing network element calculates traffic and duration of thetraffic flow, and monitors a usage extent of the credit quota of eachcharging level; the processing network element sends a credit quotacontrol update message to the online charging system and acquires anupdated credit quota when the credit quota is expired.

When the processing network element performs offline charging, thecharging for the traffic flow according to the charging strategyinformation and the user state information includes:

the processing network element calculates traffic and duration of thetraffic flow according to the charging strategy information and the userstate information, and monitors triggering of a charging event.

Preferably, an Sxx interface defined in the embodiment of the presentdisclosure is supported between the data centre management networkelement and the controller, through which the data centre managementnetwork element may receive the charging resource requesting informationfrom the controller. Furthermore, the data centre management networkelement may send control information for users from an online chargingsystem or an offline charging system implemented by a virtual machine tothe controller through the Sxx interface, then the controlleraccordingly processes user plane links. Furthermore, the controller mayrequest and acquire address or tunnel information of the processingnetwork element from the data centre management network element throughthe Sxx interface.

Step 202: the data centre management network element sends the chargingstrategy information, the user state information and the information ofthe UGW to the processing network element, and the processing networkelement then implements transmission of a traffic flow with the UGWaccording to the information of the UGW, charges for the traffic flowaccording to the charging strategy information and the user stateinformation, and feeds back charging processing information to the datacentre management network element.

Preferably, when the processing network element performs onlinecharging, the method further includes:

upon reception of a user state information change notification messagefrom the controller, the data centre management network element sendsthe user state information change notification message to the processingnetwork element;

when a charging event is triggered and a credit quota is re-granted, theprocessing network element sends a credit quota control update messageto the online charging system and acquires an updated credit quota;

when the credit quota in the online charging system is expired, theonline charging system sends a session termination message to the datacentre management network element.

Specifically, upon reception of service data to be charged from the UGW,the processing network element calculates traffic and duration of atraffic flow of each service, calculates all traffics and durations ofservices corresponding to each charging level based on the chargingstrategy information, the usage of traffic and duration being the usageof the credit quota, then monitors current remaining credit quota inreal time, and when the credit quota is expired or the condition ofcredit reauthorization is satisfied, requests a new credit quota fromthe online charging system or start a credit reauthorization process.Accordingly, the online charging system is responsible for controllingthe charging of credit quota, allocating a new credit quota orreauthorizing the credit quota to the processing network element.Moreover, when the credit quota is restricted, the online chargingsystem notifies the data centre management network element to instructthe controller to cut off the user plane link.

Preferably, when the processing network element performs offlinecharging, the method further includes:

upon reception of a user state information change notification messagefrom the controller, the data centre management network element sendsthe user state information change notification message to the processingnetwork element;

when a charging event is triggered, the processing network element sendsthe charging event and a calculation result of traffic and duration ofthe traffic flow to an offline charging system through a billingmessage: or, the processing network element sends a charging data record(CDR) of a generated calling record to the offline charging systemthrough a data record transmission message.

Step 203: the data centre management network element feeds back thecharging processing information to the controller.

Preferably, the method further includes:

when a session is terminated, the data centre management network elementnotifies the controller of a session termination message and releases auser plane channel/link by means of the controller;

when a session or a packet data protocol (PDP) context is deleted, thedata centre management network element receives a charging-relatedsession releasing message from the controller and notifies theprocessing network element to terminate charging and to report chargingprocessing information;

the data centre management network element releases resources related tothe processing network element and deletes the charging strategyinformation, the user state information and the information of the UGW.

An embodiment of the present disclosure also describes a method fornetwork charging performed by a controller. As shown in FIG. 3, saidmethod includes following steps:

Step 301: user state information from a mobility management networkelement and charging strategy information from a charging rule networkelement are received, then a charging resource request messagecontaining the charging strategy information, the user state informationand information of the UGW are sent to a data centre management networkelement.

Preferably, a S11 or Gn interface in a general packet radio servicetunnelling protocol-C (GTP-C) is supported between the controller andthe mobility management network element, which enables the controller tobe compatible with existing mobility management network element devices.The controller may acquire more user state information through the S11or Gn interface.

Preferably, a Gx interface is supported between the controller and thecharging strategy network element, which enables the controller to becompatible with an existing charging rule generation network element.The controller may acquire the charging strategy information through theGx interface.

Preferably, an enhanced Open Flow protocol is supported between thecontroller and the UGW, which enables the controller to send servicedata to be charged to a virtual machine of the data centre which is usedfor collecting charging information, i.e. a processing network element.

Preferably, the information of the processing network element includesaddress or tunnel information of the processing network element;

the charging strategy information includes a charging level, a chargingmode, a measurement method and a data usage report level;

the user state information includes a user identifier, user locationinformation, service network information, an access network type, CSGinformation, and a charging feature for a subscriber;

the information of the UGW includes address or tunnel information of theUGW.

Step 302: information of the processing network element is received fromthe data centre management network element.

Preferably, the method further includes:

a user state information change notification message is sent to the datacentre management network element, upon reception of the user stateinformation change notification message from the mobility managementnetwork element.

Step 303: a flow table is configured for the UGW according to theinformation of the processing network element, and the configured flowtable is sent to the UGW.

Step 304: charging processing information fed back from the data centremanagement network element is received when the processing networkelement charges for a traffic flow.

Preferably, the method further includes:

when a session is terminated, a session termination message from thedata centre management network element is received and a user planechannel/link is released;

when a session or a PDP context is deleted, a charging-related sessionreleasing message is sent to the data centre management network element.

An embodiment of the present disclosure also describes a data centreadapted for the above method for network charging. As shown in FIG. 4,said data centre includes a data centre management network element 41and a processing network element 42, in which

the data centre management network element 41 is configured to, uponreception of a charging resource request message from a controller,support a charging function of a processing network element by a virtualmachine and feed information of the processing network element 42 backto the controller, wherein the charging resource request messagecomprises charging strategy information, user state information andinformation of a UGW; send the charging strategy information, the userstate information and the information of the UGW to the processingnetwork element 42, and feed charging process information back to thecontroller which is fed back from the processing network element 42;

the processing network element 42 is configured to implementtransmission of a traffic flow with the UGW according to the informationof UGW, charge for the traffic flow according to the charging strategyinformation and the user state information, and feed the chargingprocessing information back to the data centre management networkelement 41.

Preferably, the data centre further includes an online charging system43 configured to send the charging processing information to the datacentre management network element;

the data centre management network element 41 is further configured tofeed the charging processing information from the online charging system43 back to the controller.

Preferably, the information of the processing network element includesaddress or tunnel information of the processing network element;

the charging strategy information includes a charging level, a chargingmode, a measurement method and a data usage report level;

the user state information includes a user identifier, user locationinformation, service network information, an access network type, CSGinformation, and a charging feature for a subscriber; and

the information of the UGW includes address or tunnel information of theUGW.

Preferably, when the processing network element performs onlinecharging,

the processing network element 42 is further configured to request andacquire a credit quota of each charging level from the online chargingsystem 43, the credit quota including traffic and duration, calculatetraffic and duration of the traffic flow, and monitor a usage extent ofthe credit quota of each charging level, send a credit quota controlupdate message to the online charging system 43 and acquire an updatedcredit quota when the credit quota is expired;

the online charging system 43 is configured to provide the credit quotaof each charging level to the processing network element 42, and providean updated credit quota to the processing network element 42 uponreception of a credit quota control update message from the processingnetwork element 42.

Preferably, when the processing network element performs onlinecharging, the processing network element 42 is further configured tocalculate traffic and duration of the traffic flow according to thecharging strategy information and the user state information, andmonitor triggering of a charging event.

Preferably, when the processing network element 42 performs onlinecharging,

the data centre management network element 41 is further configured to,upon reception of a user state information change notification messagefrom the controller, send the user state information change notificationmessage to the processing network element 42;

the processing network element 42 is further configured to, when acharging event is triggered and a credit quota is re-granted, send acredit quota control update message to the online charging system 43 andacquire an updated credit quota;

the online charging system 43 is further configured to, when the creditquota in the online charging system 43 is expired, send a sessiontermination message to the data centre management network element 41.

Preferably, when the processing network element performs offlinecharging, the data centre further includes an offline charging system44,

the data centre management network element 41 is further configured to,upon reception of a user state information change notification messagefrom the controller, send the user state information change notificationmessage to the processing network element 42;

the processing network element 42 is further configured to, when acharging event is triggered, send the charging event and a calculationresult of traffic and duration of the traffic flow to an offlinecharging system 44 through a billing message; or, send a generated CDRto the offline charging system 44 through a data record transmissionmessage;

the offline charging system 44 is configured to receive the chargingevent and the calculation result of traffic and duration of the trafficflow from the processing network element 42, or the CDR.

Preferably, the data centre management network 41 is further configuredto, when the session is terminated, notify the controller of a sessiontermination message and release a user plain channel/link by means ofthe controller; when a session or a PDP context is deleted, receive acharging-related session releasing message from the controller andnotify the processing network element 42 to terminate charging and toreport charging processing information; release resources related to theprocessing network element 42, and delete the charging strategyinformation, the user state information and the information of the UGW.

An embodiment of the present disclosure also describes a controlleradapted for the above method for network charging. As shown in FIG. 5,the controller includes a first receiving unit 51, a first sending unit52, a second receiving unit 53, a configuration unit 54, a secondsending unit 55 and a third receiving unit 56, in which

the first receiving unit 51 is configured to receive user stateinformation from a mobility management network element and chargingstrategy information from a charging rule network element;

the first sending unit 52 is configured to send a charging resourcerequest message containing the charging strategy information, the userstate information and information of a UGW to a data centre managementnetwork element;

the second receiving unit 53 is configured to receive information of theprocessing network element from the data centre management networkelement;

the configuration unit 54 is configured to configure a flow table forthe UGW according to the information of the processing network element;

the second sending unit 55 is configured to send the configured flowtable to the UGW;

the third receiving unit 56 is configured to receive charging processinginformation fed back from the data centre management network elementwhen the processing network element charges for a traffic flow.

Preferably, the information of the processing network element includesaddress or tunnel information of the processing network element;

the charging strategy information includes a charging level, a chargingmode, a measurement method and a data usage report level;

the user state information includes a user identifier, user locationinformation, service network information, an access network type, CSGinformation and a charging feature for a subscriber;

the information of UGW includes address or tunnel information of theUGW.

Preferably, the controller further includes a third sending unit 57configured to send a user state information change notification messageto the data centre management network element, upon reception of theuser state information change notification message from the mobilitymanagement network element.

Preferably, the controller further includes a releasing unit 58 and afourth sending unit 59, in which

the releasing unit 58 is configured to, when a session is terminated,receive a session termination message from the data centre managementnetwork element and release a user plane channel/link;

the fourth sending unit 59 is configured to, when a session or a packetdata protocol PDP context is deleted, send a charging-related sessionreleasing message to the data centre management network element.

An embodiment of the present disclosure also describes a system fornetwork charging adapted for the above method for network charging. Asshown in FIG. 6, said data centre includes a data centre as shown inFIG. 4, a controller as shown in FIG. 5 and a UGW 63.

It should be understood by those skilled in the art that, theimplementation of the function of the data centre 61 may be understoodwith reference to the data centre in FIG. 4, the implementation of thefunction of the controller 62 may be understood with reference to thecontroller in FIG. 5, and the implementation of the UGW 63 may beunderstood with reference to a combination of the data centre in FIG. 4and the controller in FIG. 5.

The system for network charging according to the embodiments of thepresent disclosure may implement online charging, offline charging andcontent charging. Specifically,

When the system for network charging implements online charging, theprocessing network element in the data centre specifically is astatistics network element, each statistics network element and theonline charging system being implemented in the form of a virtualmachine.

When the system for network charging implements offline charging, theprocessing network element in the data centre specifically is astatistics network element, each statistics network element and theoffline charging system being implemented in the form of a virtualmachine.

When the system for network charging implements content charging, theprocessing network element in the data centre specifically is atransmission detecting network element, the data centre including anonline charging system and an offline charging system; each of thetransmission detecting network element, the online charging system andthe offline charging system is implemented in the form of a virtualmachine.

It should be understood by those skilled in the art that, functions ofvarious apparatuses in the system for network charging and interactivemodes thereamong, etc. may be understood with reference to thedescriptions related to the previous method for network charging, datacentre, controller and UGW and will not be repeated here.

The method for network charging of the present disclosure is describedin further detail with reference to specific embodiments.

FIG. 7 is a schematic diagram of an implementation procedure of a methodof online charging according to an embodiment of the present disclosure.As shown in FIG. 7, steps 701 to 712 illustrate an implementationprocedure of online charging during the establishment of a session,steps 713 to 717 illustrate an implementation procedure of the onlinecharging when a charging condition is changed, steps 718 to 722illustrate an implementation procedure of the online charging when thecredit authorisation is terminated, and steps 723 to 727 illustrates animplementation procedure of the online charging when the session isterminated.

Step 701: a mobility management network element sends a creating sessionor a PDP context charging message to a controller.

This step is to establish a user plane channel/link. The chargingmessage includes a user identifier, a charging feature for a subscriberand the like.

Step 702: the controller acquires charging strategy information throughan interaction with a charging rule network element.

Here, the charging strategy information includes a charging level, acharging mode, a measurement method, a charging report level and thelike.

Step 703: the controller sends a charging message to a data centremanagement network element.

Here, the charging message includes charging information, requestedaddress or tunnel information of a statistics network element, user's IPaddress and information of a UGW. The charging information includes auser identifier, a charging rule and the like.

Preferably, the tunnel information of the statistics network element,which is an optional parameter, is only included in the charging messagewhen data is transmitted between the UGW and the statistics networkelement in a tunnel mode. The user's IP address may be provided by thedata centre or designated by the controller. In the case that the user'sIP address is designated by the controller, it is required that the datacentre perform a network address translation (NAT) on the user'saddress, so as to guarantee the arrival of downlink data at thestatistics network element. The information of a UGW includes address ortunnel information of the UGW, such that the statistical network elementmay perform the routing of the downlink data.

Step 704: the data centre management performs resource allocation.

Specifically, the data centre management network element implements thestatistics network element with a virtual machine, configures itsfunction and allocates address or tunnel information to the statisticsnetwork element.

Step 705: the data centre management network element issues the charginginformation and the information of the UGW to the statistics networkelement.

In this way, the statistics network element may identify therelationship between the service data and the charging rule and send thedownlink data to the UGW through an IP or a tunnel.

Step 706: the processing network element acquires a credit quota of eachcharging level from the online charging system.

Here, the credit quota includes traffic and duration of the servicedata.

Step 707: the data centre management network element sends the addressor tunnel information of the statistics network element and the IPaddress allocated by the data centre for a user to the controller inresponse to the charging message from the controller.

Step 708: the controller generates a flow table for the UGW.

In this way, the UGW may designate a routing for routing the trafficflow to be charged online to the statistics network element of the datacentre according to the charging rule.

Step 709: the controller sends the flow table for the UGW with anOFPT_FLOW_MOD message of the Open Flow protocol.

Step 710: uplink data may be transmitted between the UGW and thestatistics network element by an IP or a tunnel.

Step 711: the statistics network element of the data centre calculatesthe traffic and duration of the data and monitors the usage of thecredit quota.

Step 712: when the credit quota is expired, the statistics networkelement sends a credit control update message to acquire a new creditquota.

Step 713: the mobility management network element informs the controllerof a user state change message using a carrying or PDP contextmodification message when the access state information of the userchanges, such that the mobility management network element supportscharging.

Step 714: the controller informs the data centre management networkelement when the controller finds any change of the user state.

Step 715: the controller sends the access state information of the userto the data centre management network element through a notificationmessage.

Step 716: the data centre management network element notifies thestatistics network element of the user state.

Step 717: when the charging triggering event and the condition of creditauthorisation are satisfied, the statistics network element acquires thenew credit quota from the online charging system through the creditcontrol update message.

Step 718: when the credit quota of the user in the online chargingsystem is expired, the online charging system sends a sessiontermination message to the data centre management network element.

Step 719, 720: the date centre management network element releasesvirtual machine resources of the statistics network element whencharging resources are not in need.

Step 721: the data centre management network element notifies thecontroller of a session termination message in a feedback message, andthe controller releases the user plane channel/link.

Step 722: the controller deletes information in the flow table relatedto the user online charging data, notifies the mobility managementnetwork element to delete information related to wireless carrying.

Step 723: the network deletes the session or PDP context due to a logoutby the user or invalid subscription.

Step 724: the controller notifies the data centre management networkelement of the releasing of the session related to the online chargingthrough a notification message. The data centre management networkelement further notifies the statistics network element to send a creditcontrol termination message to the online charging system.

Step 725, 726: the data centre management network element releases thestatistics virtual machine resources related to the online charging,deletes information such as the charging rule and user identifier whenthe online charging function is not in need.

Step 727: the controller deletes information related to the user onlinecharging data from the flow table.

FIG. 8 is a schematic diagram of an implementation procedure of themethod of offline charging according to an embodiment of the presentdisclosure. As shown in FIG. 8, steps 801 to 810 illustrate animplementation procedure of an offline charging during the establishmentof a session, steps 811 to 815 illustrate an implementation procedure ofthe offline charging during the change of charging condition, and steps816 to 820 illustrates an implementation procedure of the offlinecharging during the termination of the session.

Step 801: a mobility management network element sends a creating sessionor PDP context charging message to a controller.

This step is to establish a user plane channel/link. The chargingmessage includes a user identifier, a charging feature for a subscriberand the like.

Step 802: the controller acquires charging strategy information throughan interaction with a charging rule network element.

Here, the charging strategy information includes a charging level, acharging mode, a measurement method, a charging report level and thelike.

Step 803: the controller sends a charging message to a data centremanagement network element.

Here, the charging message includes charging information, requestedaddress or tunnel information of a statistics network element, user's IPaddress and information of a UGW. The charging information includes auser identifier, a charging rule and the like.

Preferably, the tunnel information of the statistics network element,which is an optional parameter, is only included in the charging messagewhen data is transmitted between the UGW and the statistics networkelement in a tunnel mode. The user's IP address may be provided by thedata centre or designated by the controller. In the case that the user'sIP address is designated by the controller, it is required that the datacentre perform an NAT on the user's address, so as to guarantee thearrival of downlink data at the statistics network element. Theinformation of UGW includes address or tunnel information of the UGW,such that the statistics network element may perform the routing of thedownlink data.

Step 804: the data centre management performs resource allocation.

Specifically, the data centre management network element implements thestatistics network element with a virtual machine, configures itsfunction and allocates address or tunnel information thereto.

Step 805: the data centre management network element issues the charginginformation and the information of the UGW to the statistics networkelement.

In this way, the statistics network element may identify therelationship between the service data and the charging rule and send thedownlink data to the UGW through an IP or a tunnel.

Step 806: the data centre management network element sends the addressor tunnel information of the statistics network element and the IPaddress allocated for the user by the data centre to the controller inresponse to the charging message from the controller.

Step 807: the controller generates a flow table for the UGW.

In this way, the UGW may designate a routing for the traffic flow to beonline charged to the statistics network element of the data centreaccording to the charging rule.

Step 808: the controller sends the flow table for the UGW with anOFPT_FLOW_MOD message of the Open Flow protocol.

Step 809: uplink data may be transmitted between the UGW and thestatistics network element through an IP or a tunnel.

Step 810: the statistics network element of the data centre calculatesthe traffic and duration of the data and monitors the usage of thecredit quota.

Step 811: the mobility management network element informs the controllerof a user state change message using a carrying or PDP contextmodification message when the access state information of the userchanges, such that the mobility management network element supportscharging.

Step 812: the controller informs the data centre management networkelement when the controller finds any change of the user state.

Step 813: the controller sends the access state information of the userto the data centre management network element through a notificationmessage.

Step 814: the data centre management network element notifies thestatistics network element of the user state.

Step 815: when the change of the user state satisfies a charging event,the statistics network element sends the charging event and statisticsinformation to an offline charging network element though a chargingmessage, or sends a charging data record (CDR) of a generated callingrecord to the offline charging network element through a data recordtransmission message. The former is adapted for an Rf interfacesupported between the statistics network element and the offlinecharging network element, and the latter is adapted for a Ga Interfacesupported between the statistics network element and the offlinecharging network element.

Step 816: the network deletes a session or PDP context due to a logoutby the user or invalid subscription.

Step 817: the controller notifies the data centre management networkelement of the releasing of the session related to the offline chargingthrough a notification message. The data centre management networkelement further notifies the statistics network element to report thestatistical information to the offline charging system through thecharging message or the data record transmission message.

Step 818, 819: the data centre management network element releases thestatistical virtual machine resources related to the online charging,deletes information such as the charging rule and user identifier whenthe charging resources are not in need.

Step 820: the controller deletes information related to the user offlinecharging data from the flow table.

FIG. 9 is a schematic diagram of an implementation procedure of a methodof network content charging according to an embodiment of the presentdisclosure. As shown in FIG. 9, steps 901 to 914 illustrate animplementation procedure of an content charging during the establishmentof a session, steps 915 to 919 illustrate an implementation procedure ofthe content charging during the change of charging condition, steps 920to 924 illustrate an implementation procedure of the content chargingduring the termination of the credit authorisation (only adapted foronline charging), and steps 925 to 929 illustrates an implementationprocedure of the content charging during the termination of the session.

Step 901: a mobility management network element sends a creating sessionor PDP context charging message to a controller.

This step is to establish a user plane channel/link. The chargingmessage includes a user identifier, a charging feature for a subscriberand the like.

Step 902: the controller acquires charging strategy information throughan interaction with a charging rule network element.

Here, the charging strategy information includes: charging level,charging mode, measurement method, charging report level and the like.

Step 903: the controller sends a charging message to a data centremanagement network element.

Here, the charging message includes: charging information, requestedaddress or tunnel information of a statistics network element, user's IPaddress and information of a UGW. The charging information includes useridentifier, charging rule and the like.

Preferably, the tunnel information of the statistics network element,which is an optional parameter, is only included in the charging messagewhen data is transmitted between the UGW and the statistics networkelement in tunnel mode. The user's IP address may be provided by thedata centre or designated by the controller. In the case that the user'sIP address is designated by the controller, it is required that the datacentre perform an NAT on the user's address, so as to guarantee thearrival of downlink data at the statistics network element. Theinformation of UGW includes address or tunnel information of the UGW,such that the statistical network element may perform the routing of thedownlink data.

Step 904: the data centre management performs resource allocation.

Specifically, the data centre management network element implements adata centre transmission and detection network element with a virtualmachine, configures functions of the data centre transmission anddetection network element such as collecting data, controlling onlinecharging credit, reporting offline charging information, etc., allocatesaddress and/or user plane tunnel information to the data centretransmission and detection network element.

Step 905: the data centre management network element issues the charginginformation and the information of the UGW to the data centretransmission and detection network element.

In this way, the data centre transmission and detection network elementmay identify the relationship between the applications and the chargingrule and send the downlink data to the UGW in IP or tunnel mode. Thedata centre transmission and detection network element may request acredit quota for content charging from the data centre content chargingsystem, and detects and calculates the data received in downlink.

Step 906: the data centre management network element sends the addressor tunnel information of the content charging system and the IP addressallocated to the user by the data centre to the controller in responseto the charging message from the controller.

Step 907: the controller generates a flow table for the UGW.

In this way, the UGW designates a route for routing the service dataidentified to need content charging according to the charging rule tothe data centre transmission and detection network element of the datacentre to perform content charging, and designates the routing of theservice data which cannot be identified according to the charging ruleto the data centre transmission and detection network element of thedata centre to perform content detection and charging.

Step 908: the controller sends the flow table for the UGW with anOFPT_FLOW_MOD message of the Open Flow.

Step 909: uplink data may be transmitted between the UGW and the datacentre transmission and detection network element in IP or tunnel mode.

Step 910: the data centre transmission and detection network elementimplements functions of data detection and statistics on the receiveduplink traffic flow.

Step 911: the data centre transmission and detection network elementimplements a function of online or offline charging.

For example, this may be reauthorization of credit quota of onlinecharging, statistics of traffic and duration of online and offlinecharging, etc.

Step 912: the data centre transmission and detection network elementdetects application type in the traffic flow and reports it to the datacentre management network element, which feeds back the application typeto the controller.

In this way, the controller may acquire the applications carried in theservice data corresponding to the flow table.

Step 913: after the controller acquires application information, thecontroller maintains the traffic flow forwarded to the data centretransmission and detection network element of the data centre whencontent charging for the traffic flow is needed, and forwards thetraffic flow from the UGW to external network servers directly whencontent charging for the traffic flow is not needed.

Step 914: the controller issues the flow table to designate a newrouting forward mode after acquiring the application information.

Step 915: the mobility management network element informs the controllera user state change message using a carrying or PDP context modificationmessage when the access state information of the user changes, such thatthe mobility management network element supports charging.

Step 916: the controller informs the data centre management networkelement when the controller finds any change of the user state.

Step 917: the controller sends the access state information of the userto the data centre management network element through a notificationmessage.

Step 918: the data centre management network element notifies the datacentre transmission and detection network element of the user state.

Step 919: when the data centre transmission and detection networkelement performs online charging, and when the change of the user statesatisfies the charging triggering event and the condition of creditauthorisation, the data centre transmission and detection networkelement acquires the new credit quota from the data centre contentcharging system through the credit control update message. When the datacentre transmission and detection network element performs offlinecharging, and when the change of the user state satisfies the chargingtriggering event, the data centre transmission and detection networkelement reports the charging event and statistical information to theoffline charging network element.

Step 920: when the credit quota of the user in the data centre contentcharging system is expired, the data centre content charging systemsends a session termination message to the data centre managementnetwork element.

Step 921, 922: the date centre management network element releasesvirtual machine resources of the data centre transmission and detectionnetwork element when charging resources are not in need.

Step 923: the data centre management network element notifies thecontroller of a session termination message through a feedback message,and the controller releases the user plane channel/link.

Step 924: the controller deletes information in the flow table relatedto the user content charging data, notifies the mobility managementnetwork element to delete wireless carrying.

Step 925: the network deletes the session or PDP context due to a logoutby the user or invalid subscription.

Step 926: the controller notifies the data centre management networkelement of the releasing of the session related to the content chargingthrough a notification message. The data centre management networkelement further notifies the data centre transmission and detectionnetwork element to terminate the online or offline charging session andto report the statistical information.

Step 927, 928: the data centre management network element releases thetransmission and detection virtual machine resources related to thecontent charging, deletes information such as the charging rule and useridentifier.

Step 929: the controller deletes information in the flow table relatedto the user content charging data.

The present disclosure also describes a storage medium in which acomputer programme is stored, which is configured to any method fornetwork charging according previous embodiments.

Above descriptions are merely preferred embodiments of the presentdisclosure, but not to limit the scope of protection of the presentdisclosure.

INDUSTRIAL APPLICABILITY

The technical scheme of the present disclosure implements the chargingservice of a SDN EPC network simply with low cost and high universality.

The invention claimed is:
 1. A method for network charging, comprising:supporting, by a data centre management network element device, acharging function of a processing network element device by a virtualmachine upon receiving a charging resource request message from acontroller device, and feeding back information of the processingnetwork element device to the controller device, wherein the chargingresource request message comprises charging strategy information, userstate information and information of a universal gateway (UGW); Sending,by the data centre management network element device, the chargingstrategy information, the user state information and the information ofthe UGW to the processing network element device; implementing, by theprocessing network element device, transmission of a traffic flow withthe UGW according to the information of the UGW, charging for thetraffic flow according to the charging strategy information and the userstate information, and feeding back charging processing information tothe data centre management network element device; and feeding back, bythe data centre management network element device, the chargingprocessing information to the controller device; wherein when theprocessing network element device performs online charging, the chargingfor the traffic flow according to the charging strategy information andthe user state information comprises: the processing network elementdevice requests and acquires from the online charging system a creditquota of each charging level, the credit quota comprising traffic andduration; the processing network element device calculates traffic andduration of the traffic flow, and monitors a usage extent of the creditquota of each charging level; and the processing network element devicesends a credit quota control update message to the online chargingsystem and acquires an updated credit quota when the credit quota isexpired.
 2. The method for network charging according to claim 1,further comprising: feeding back, by the data centre management networkelement device, upon reception of the charging processing informationfrom an online charging system, the charging processing information tothe controller device.
 3. The method for network charging according toclaim 1, further comprising: when the processing network element deviceperforms online charging, sending, by the data centre management networkelement device, upon reception of a user state information changenotification message from the controller device, the user stateinformation change notification message to the processing networkelement device; sending, by the processing network element device, whena charging event is triggered and a credit quota is re-granted, a creditquota control update message to the online charging system and acquiringan updated credit quota; sending, by the online charging system, whenthe credit quota in the online charging system is expired, a sessiontermination message to the data centre management network elementdevice.
 4. The method for network charging according to claim 1, whereinwhen the processing network element device performs offline charging,the charging for the traffic flow according to the charging strategyinformation and the user state information comprises: the processingnetwork element device calculates traffic and duration of the trafficflow according to the charging strategy information and the user stateinformation, and monitors triggering of a charging event.
 5. The methodfor network charging according to claim 4, further comprising: when theprocessing network element device performs offline charging, sending, bythe data centre management network element device, upon reception of auser state information change notification message from the controllerdevice, the user state information change notification message to theprocessing network element device; sending, by the processing networkelement device, when the charging event is triggered, the charging eventand traffic and duration of the traffic flow to an offline chargingsystem through a billing message; or, sending, by the processing networkelement device, a charging data record (CDR) of a generated callingrecord to the offline charging system through a data record transmissionmessage.
 6. The method for network charging according to claim 1,further comprising: notifying, by the data centre management networkelement device, when a session is terminated, the controller of asession termination message, and releasing a user plane channel/link bymeans of the controller device; when a session or a packet data protocol(PDP) context is deleted, receiving, by the data centre managementnetwork element device, a charging-related session releasing messagefrom the controller device and notifying the processing network elementdevice to terminate charging and to report charging processinginformation; releasing, by the data centre management network elementdevice, resources related to the processing network element device anddeleting the charging strategy information, the user state informationand the information of the UGW.
 7. A data centre, comprising: a datacentre management network element device and a processing networkelement device, wherein the data centre management network elementdevice is configured to, upon reception of a charging resource requestmessage from a controller device, support a charging function of aprocessing network element device by a virtual machine and feedinformation of the processing network element device back to thecontroller device, wherein the charging resource request messagecomprises charging strategy information, user state information andinformation of a universal gateway (UGW); and configured to send thecharging strategy information, the user state information and theinformation of the UGW to the processing network element device, feedcharging process information which is fed back from the processingnetwork element device back to the controller device; the processingnetwork element device is configured to implement transmission of atraffic flow with the UGW according to the information of the UGW,charge for the traffic flow according to the charging strategyinformation and the user state information, and feed the chargingprocessing information back to the data centre management networkelement device; wherein when the processing network element deviceperforms online charging, the processing network element is furtherconfigured to request and acquire a credit quota of each charging levelfrom the online charging system, the credit quota comprising traffic andduration, calculate traffic and duration of the traffic flow, andmonitor a usage extent of the credit quota of each charging level; andconfigured to send a credit quota control update message to the onlinecharging system and acquire an updated credit quota when the creditquota is expired; the online charging system is configured to providethe credit quota of each charging level to the processing networkelement device when receiving the request from the processing networkelement device, and provide the updated credit quota to the processingnetwork element device upon reception of the credit quota control updatemessage from the processing network element device.
 8. The data centreaccording to claim 7, wherein the data centre further comprises anonline charging system configured to send the charging processinginformation to the data centre management network element device; thedata centre management network element device is further configured tofeed the charging processing information from the online charging systemback to the controller device.
 9. The data centre according to claim 7,wherein when the processing network element device performs onlinecharging, the data centre management network element device is furtherconfigured to, upon reception of a user state information changenotification message from the controller device, send the user stateinformation change notification message to the processing networkelement device; the processing network element is further configured to,when a charging event is triggered and a credit quota is re-granted,send a credit quota control update message to the online charging systemand acquire an updated credit quota; the online charging system isfurther configured to, when the credit quota in the online chargingsystem is expired, send a session termination message to the data centremanagement network element device.
 10. The data centre according toclaim 7, wherein when the processing network element device performsonline charging, the processing network element device is furtherconfigured to calculate traffic and duration of the traffic flowaccording to the charging strategy information and the user stateinformation, and monitor triggering of a charging event.
 11. The datacentre according to claim 10, wherein when the processing networkelement performs offline charging, the data centre further comprises anoffline charging system, the data centre management network elementdevice is further configured to, upon reception of a user stateinformation change notification message from the controller device, sendthe user state information change notification message to the processingnetwork element device; the processing network element is furtherconfigured to, when the charging event is triggered, send the chargingevent and traffic and duration of the traffic flow to an offlinecharging system through a billing message; or, send a charging datarecord (CDR) of a generated calling record to the offline chargingsystem through a data record transmission message; the offline chargingsystem is configured to receive from the processing network elementdevice the charging event and a calculation result of the traffic andduration of the traffic flow, or the CDR.
 12. The data centre accordingto claim 7, wherein the data centre management network element device isfurther configured to, when a session is terminated, notify thecontroller of a session termination message and release a user plainchannel/link by means of the controller device; when a session or apacket data protocol (PDP) context is deleted, receive acharging-related session releasing message from the controller deviceand notify the processing network element device to terminate chargingand to report charging processing information; release resources relatedto the processing network element device, and delete the chargingstrategy information, the user state information and the information ofthe UGW.